Atlanta (CNN) -- In what has been described as one of the largest cheating scandals to hit the nation's public education system, 35 Atlanta Public Schools educators and administrators were indicted Friday on charges of racketeering and corruption.

The indictment is the bookend to a story that was once touted as a model for the nation's school districts after the district's test scores dramatically improved in some of its toughest urban schools.

Among those indicted by a Fulton County, Georgia, grand jury was Beverly Hall, the former schools superintendent who gained national recognition in 2009 for turning around Atlanta's school system.

"She was a full participant in that conspiracy," Fulton County District Attorney Paul Howard told reporters during a news conference announcing the charges.

"Without her, this conspiracy could not have taken place, particularly in the degree in which it took place."

The indictment follows a state investigation that was launched after a series of reports by The Atlanta Journal-Constitution newspaper found large, unexplained gains in test scores in some Atlanta schools.

A state review determined that some cheating had occurred in more than half of the district's elementary and middle schools. About 180 teachers were initially implicated in the scandal.

2011: Quit or be fired, educators implicated in Atlanta scandal told

Threats and intimidation

Hall has denied any role in the cheating scandal. In 2011, she told The New York Times that her subordinates had allowed the cheating to occur, but denied she was involved.